<span *ngFor="let holder of placeHolders; index as i"
    [class.empty]="isInputElementEmptyAt(i)"
    [class.code-hidden]="isCodeHidden"
    class="code-hiddena">
        <form>
        
        <input #input
            maxlength="1"
            (input)="onInput($event, i)"
            (keydown)="onKeydown($event, i)"
            type="tel" />
        </form>
</span>
